<html>
 <head>
  <link href="./leetcode-problem.css" rel="stylesheet" type="text/css">
 </head>
 <body>
  <div class="question_difficulty">
   难度：Easy
  </div>
  <div>
   <h1 class="question_title">
    217. Contains Duplicate
   </h1>
   <p>
    Given an array of integers, find if the array contains any duplicates.
   </p>
   <p>
    Your function should return true if any value appears at least twice in the array, and it should return false if every element is distinct.
   </p>
   <p>
    <strong>
     Example 1:
    </strong>
   </p>
   <pre>
<strong>Input:</strong> [1,2,3,1]
<strong>Output:</strong> true</pre>
   <p>
    <strong>
     Example 2:
    </strong>
   </p>
   <pre>
<strong>Input: </strong>[1,2,3,4]
<strong>Output:</strong> false</pre>
   <p>
    <strong>
     Example 3:
    </strong>
   </p>
   <pre>
<strong>Input: </strong>[1,1,1,3,3,4,3,2,4,2]
<strong>Output:</strong> true</pre>
  </div>
  <div>
   <h1 class="question_title">
    217. 存在重复元素
   </h1>
   <p>
    给定一个整数数组，判断是否存在重复元素。
   </p>
   <p>
    如果任何值在数组中出现至少两次，函数返回 true。如果数组中每个元素都不相同，则返回 false。
   </p>
   <p>
    <strong>
     示例 1:
    </strong>
   </p>
   <pre><strong>输入:</strong> [1,2,3,1]
<strong>输出:</strong> true</pre>
   <p>
    <strong>
     示例 2:
    </strong>
   </p>
   <pre><strong>输入: </strong>[1,2,3,4]
<strong>输出:</strong> false</pre>
   <p>
    <strong>
     示例&nbsp;3:
    </strong>
   </p>
   <pre><strong>输入: </strong>[1,1,1,3,3,4,3,2,4,2]
<strong>输出:</strong> true</pre>
  </div>
 </body>
</html>